1. Field of the Invention
The present invention relates to a core for a deflecting yoke (deflection yoke) and to a deflecting yoke (deflection yoke), which are used for a CRT (Cathode Ray Tube) and capable of enhancing a deflection sensitivity and reducing electric power consumed.
2. Description of the Prior Art
A conventional CRT is constructed of a display panel, a funnel and a neck. A core for a deflection yoke is provided covering some portions of the funnel and the neck. The deflection yoke using such a deflection yoke core deflects an electron beam emitted from an electron gun provided at the neck. In the typical deflection yoke core, configurations of neck-and funnel-side aperture edge surfaces are circular, and the deflection yoke is constructed in such a way that horizontal and vertical windings called a saddle type coil are provided on the side of an inner surface of the core.
According to, e.g., Japanese Patent Publication No.8-28194, as shown in FIGS. 1 through 3, a deflection yoke core (a round uniform slot type core) 1 of which a sectional configuration is circular includes a plurality of protruded portions 1a provided consecutively from a side (a neck side) with an inner surface having a small diameter toward a side (a funnel side) having a large diameter, and grooved portions 1b are formed between the protruded portions 1a. Windings (vertical and horizontal windings) 4 are, as shown in FIG. 4, disposed in the grooved portions 1b, thus constructing a winding structure known as a slot system. FIG. 1 is a diagram of the deflection yoke core 1 as viewed from the funnel side, FIG. 2 is a diagram of the deflection yoke core 1 as viewed from the neck side, and FIG. 3 is a diagram showing an external portion 5a and a sectional portion 5b of the deflection yoke core 1.
In the deflection yoke core disclosed in Japanese Patent Publication No.8-28194, however, a sectional configuration of the CRT on the funnel side is circular, and, in the case of using this core, a geometrical distortion property and a mis-convergence property of the deflection yoke are substantially equal to the properties in the case of a typical deflection yoke core. Therefore, despite such a main trend that a sectional configuration of the display panel of the CRT is a rectangle exhibiting an aspect ratio of 4:3 or 16:9, a configuration of a portion, fitted with the deflection yoke, of the CRT is circular in terms of a manufacturing problem, with the result that there might be a limit in terms of enhancing the deflection sensitivity of the electron beam.
Further, Japanese Patent Application Laid-Open Publication Nos.8-7781 and 8-7792 each disclose a deflection yoke core, wherein the sectional configuration is, as shown in FIG. 5, an ellipse other than the circle. Referring again to FIG. 5, an outer surface configuration of a funnel-side section is an ellipse as indicated by four circular segments ab, bc, cd, da. In particular, the circular segments ab, cd have radii R1 having the same length, of which the center is an origin O of the X- and Y-axis coordinates. The circular segments bc, da have radii R2 having the same length, of which centers are symmetrical points S. S' on the Y-axis. Herein, let P, Q be nodal points between the circular segments bc, da and the Y-axis, and there is established a relationship such as OP (OQ)&lt;R1. A capacity of the cone portion is thereby made smaller than that of the circular core, thus reducing deflection power. Further, the outer surface configuration of the core 2 is, as shown in FIG. 5, so formed as to contain the circular segment having the maximum radius R1 of which the center is the origin O of the X- and Y-axis coordinates. With this contrivance, a conventional sintering frame 3 for the circular core, which is formed with an aperture 3a having the radius R1 as indicated by the broken line in FIG. 5, can be used when manufacturing the core assuming the elliptical configuration of the outer surface by sintering.
In the deflection yoke core disclosed in Japanese Patent Application Laid-Open Publication No.8-7781, however, in order to make usable the conventional sintering frame formed with the round aperture when in the sintering process, the funnel-side outer surface configuration is elliptical, and there is neither disclosed anything about an inner surface configuration thereof nor mentioned specifically an improvement of a deflection sensitivity.